The proposed project attempts to establish relationships between reproductive behavioral activity and steroid hormones by using appropriate animal model systems. To study the regulation of female behavior by cellular actions of hormones we will examine estrogen and progesterone uptake mechanisms in particular brain areas of female guinea pigs. Female behavioral events will be correlated with steroid receptor levels and the influence of steroid antagonists on behavior and on receptors will be investigated. Not only do steroids influence behavior, but behavior also influences steroids. The effects of behavioral and environmental factors on androgen secretion in male guinea pigs and ring doves will be studied. These experiments relate to psychosomatic influences on reproduction and will utilize radioimmunoassay methods and manipulation of neurotransmitter levels by means of receptor agonists and neurotoxins. The reasons underlying individual differences in male reproductive behavior of guinea pigs and the relation of these differences to psychosomatic factors will also be investigated.